In liquid detergent compositions, especially those for the washing of textile fabrics, it is common to include one or more enzymes for assisting removal of various kinds of soil. Amongst these are proteolytic enzymes, often referred to as “proteases”. Proteases are used to assist in the removal of protein-based soil.
However, the very nature and activity of these enzymes means that they attack any other component in the liquid composition which has a protein-like structure. As a result, they can degrade other enzymes in the liquid, as well as undergo self-degradation. To counteract this, it is usual also to incorporate an enzyme stabilising system. Such stabilising systems commonly consist of a boron compound, e.g. borax, together with a polyol, e.g. glycerol or sorbitol. These components are believed to form an enzyme-inhibiting complex which dissociates by dilution of the composition into the wash liquor, disabling the inhibiting effect so that the protease can act upon the proteinaceous soil.
Other protease stabilisers such as calcium chloride/calcium format are also known but are not as effective as those systems based on boron. On the other hand, it may be desirable for environmental reasons to reduce the amount of boron in the detergent composition.
Another type of enzyme stabilising system for use in enzyme-containing liquid detergent compositions is disclosed by U.S. Pat. No. 4,238,345. This document discloses that the combination of an antioxidant having a standardised redox potential at least equal to that of ascorbic acid but less than that of sodium hydrosulphite, with hydrophylic polyol is an effective stabilising system for proteolytic enzymes.
We have found in this connection that perfumes generally can degrade proteolytic and lipolytic enzymes when also present in liquid detergent compositions. In particular, we have found that some specific perfume components particularly degrade protease and lipase enzymes when present in the liquid detergent composition.
In view of this, it is an object of the present invention to provide an effective liquid detergent composition containing both a proteolytic and/or lipolytic enzyme and a perfume composition, and having favourable storage stability.
We have now surprisingly found that this object can be achieved by using a perfume composition in the liquid detergent composition, and combining it with an antioxidant.
In other words, we have found that a protease and/or lipase-containing liquid detergent composition having favourable storage stability characteristics can be obtained, when that composition contains an antioxidant in combination with a perfume composition.